ESTRO 2021 Abstract Book

S833

ESTRO 2021

Conclusion In our analysis, pts addressed to our Dpt for a HN cancer in 2020 presented more advanced stages when compared to 2019. The follow-up of pts was too short to present data on LC and OS in this abstract, but clinical data will be presented during the congress. PO-1001 The effect of switching to carboplatin chemo-RT for cycle 2 in cisplatin-ineligible HNSCC patients J. Price 1,2 , I. Fornacon-Wood 2 , D. Thomson 1,2 , L. Lee 1 , A. Sykes 1 , K. Garcez 1 , G. Price 2 , A. McPartlin 1,2 1 The Christie NHS Foundation Trust, Department of Clinical Oncology, Manchester, United Kingdom; 2 The University of Manchester, Division of Cancer Sciences, Faculty of Biology, Medicine and Health, Manchester, United Kingdom Purpose or Objective For fit patients with locally advanced head and neck squamous cell carcinoma (HNSCC), radiotherapy (RT) concurrent with two cycles of high-dose cisplatin chemotherapy (CDDP) is the standard of care. It is accepted that both cycles are required in order to achieve optional survival outcomes, but some patients may become CDDP-ineligible after cycle one (e.g., secondary to renal dysfunction, peripheral neuropathy or hearing loss). For these patients, the substitution of an alternative platinum-containing regimen is an option, but there is little evidence to guide this approach. For patients who become ineligible for cycle two CDDP, this study investigates the effect on outcomes of (i) switching to carboplatin for cycle two of chemo-RT or (ii) continuing with RT alone. Materials and Methods The institutional database was searched for all patients with AJCC (7 th edition) stage III-IVb HNSCC treated with definitive RT and concurrent CDDP between 2009 and 2017. Demographic, clinico-pathological and outcome data were recorded. Multivariable cox proportional hazard survival models were fit to predict overall survival (OS) and freedom from relapse (FFR), adjusting for ECOG performance status, tumour and nodal stage, smoking status and use of induction chemotherapy. Results Complete records for 725 patients were available, with 192 deaths and 145 failure events. Median follow-up duration for OS was 64 months (range 62 to 67 months) and for FFR was 50 months (range 47 to 53.4 months). 529 patients (73%) completed the scheduled two cycles of CDDP, 65 (9%) switched to carboplatin for cycle two and 131 (18%) did not receive a second cycle of chemotherapy. Reasons for omitting cycle two CDDP included: treatment side effects (n = 78), renal impairment (n = 75), hearing loss (n = 15), neutropenia (n = 12), cardiac toxicity (n = 5), anaemia (n = 2), peripheral neuropathy and allergic reaction (both n = 1). Compared to two cycles of CDDP, a single cycle and no further chemotherapy was associated with significantly reduced FFR (HR = 1.74, 95% CI 1.18-2.57, p=0.005; Figure 1a) and OS (HR = 1.65, 95% CI 1.16-2.35, p=0.005; Figure 1b) Switching from CDDP to carboplatin for cycle 2 was not associated with inferior FFR (HR = 1.10, 95% CI 0.614-1.96, p=0.753) or OS (HR = 1.2, 95% CI 0.72-2.01, p = 0.487).